1. Field of the Invention
The invention concerns an optical fiber connector that permits one or more optical fibers to be disconnectably fastened in a single motion to make low-loss connections either to other optical fibers or to a lens or an opto-electronic element.
2. Description of the Related Art
A variety of connectors are being marketed for disconnectably fastening in a single motion one or more optical fibers either to other optical fibers or to an opto-electronic element. Almost all such connectors are assembled using an adhesive to secure the optical fiber or fibers. To assemble such a connector, the protective coverings are stripped from one end of one or more optical fibers, and the bare end of each fiber is fed into a channel of a fitting while employing an adhesive to bond it to the fitting. Then after polishing the end of the fitting and each adhered fiber, the assembled connector can be fastened to or removed from a receptacle in one motion, thus making a low-loss connection either to an opto-electronic element or to the optical fiber or fibers of an identical connector.
Not only are adhesives messy, polluting and possibly toxic, but their use requires some skill. Furthermore, the adhesive is typically supplied with the warning that it is no longer useful after a certain period of time, e.g., six months.
Among a number of such connectors now being marketed by NEC Electronics, Inc. of Mountain View, Calif., are "FC Type Single-Mode Fiber-Optic Connectors," the assembly of which is described in a pamphlet marked "NECEL-000321-0785" and "Stock No. 836276" and is dated July 1985. Its assembly includes the steps of: (1) strip the cable's outer sheath and jacket to bare an end of the optical fiber, (2) apply adhesive both to the inside of a terminal and to the exposed fiber, (3) insert the coated fiber into the terminal, (4) mechanically fasten the terminal into a ferrule that is formed to permit the fiber to be mechanically interconnected with another fiber or an opto-electronic element, (5) put a small amount of adhesive on the tip of the terminal, (6) heat to cure the adhesive, (7) cleave (cut off) the protruding portion of the fiber, and (8) polish until the terminal end and the fiber face have a glassy appearance.
Connectors similar to the above-discussed NEC snap-on connector that are assembled with adhesive are described in sales literature of ITT Cannon, Fountain Valley, Calif. ("SFOGP-1" dated June 1983); Daini Seikosha Co., Ltd., for its optical fiber connector SAP-2, SF-1; and Augat Fiberoptics of Pawtucket, RI ("F-2938") dated 1985.
A class of connectors that are assembled without an adhesive and yet permit one or more optical fibers to be disconnectably fastened in a single motion are "Crimp and Cleave" connectors from Ensign-Bickford Optics Co., Avon Conn., and "Crimp Style" connectors from Augat Electronics. Their assembly includes the steps of: (1) strip to bare an end of the optical fiber, (2) crimp a ring over the stripped back Kevlar and outer sheath, (3) slip the bare fiber into a bore of a terminal that also fits over said ring, (4) crimp the terminal to the ring, and (5) cleave the protruding portion of the fiber. Because these connectors do not hold the fiber against longitudinal movement, their cleaved faces are not polished. Hence, these connectors do not provide low-loss connections.
A connector that is assembled without adhesive, but does not make connections in a single motion, is described in U.S. Pat. No. 4,155,624 (Logan et al.), FIGS. 1-10 of which illustrate the interconnection of two pairs of optical fibers while also supporting them with respect to a wall 26 or bulkhead. The stripped ends 46,48 of two parallel optical fibers are laid into a rectangular recess 62 and V-notch 64 of a fiber support section 60 and cut with a razor blade to extend about one half the length of the section 60. The stripped ends of another two optical fibers (not shown) are similarly positioned in the rectangular recess and V-notch of an identical fiber support section 74 so that when the two fiber support sections are mechanically joined as shown in FIG. 6, the two sets of "fibers generally meet end-to-end or with a small separation" (col. 3, is. 61-62). Other elements of Logan's mechanical connector grip the cables covering the optical fibers, thus preventing axial movement within the interconnected sections 60,74.
In order to disconnect fibers that have been interconnected by the Logan device, it would need to be disassembled. Reconnection would require the whole procedure to be repeated.
U.S. Pat. No. 4,470,180 (Blomgren) shows devices that can be used to interconnect the stripped ends of a pair of optical fibers by means of a combination of a grooved mount and a deformable housing. In its normal state, the housing grips the optical fiber against a groove in the mount, but releases that stripped end when deformed.